1. Field of the Invention
The present invention relates to a power generation system using a power generation apparatus, which outputs alternating voltages by an input of vibrations, and outputting electric powers, which are generated by the power generation apparatus, to a load instrument.
2. Description of the Related Art
Japanese Patent Gazette No. 4905820 sets forth a magnetostrictive element as a power generation apparatus which outputs alternating voltages by an input of vibrations. A plurality of the power generation apparatuses generate electric powers by the vibrations of vibrating bodies with frequencies which differ respectively. That is, the timing, at which each of the power generation apparatuses generates electricity, differs.
Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2012-160620, and Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2012-152009 set forth voltage-doubling rectifier circuits, respectively, as a circuit rectifying alternating voltages. It is possible for the voltage-doubling rectifier circuits to make an output voltage higher to such an extent as much as twice by making it possible to store electricity in capacitors to which each of the bidirectional voltages of alternating voltages correspond. Japanese Unexamined Patent (KOKAI) Gazette No. 2001-211606 sets forth a full-wave rectifier circuit as a circuit which rectifies alternating voltages.
Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2013-102639 sets forth storing electricity efficiently in an electricity storage portion by switching from a state where a plurality of power generation portions are connected in series, to another state where the multiple power generation portions are connected in parallel, or vice versa.
Incidentally, in order to enhance an output voltage, connecting a plurality of units, which include a power generation apparatus and a rectifier circuit, in series is thought of. In this instance, it was understood that, when one of the rectifier circuits constructing at least one of the multiple power-generation circuital units is a voltage-doubling rectifier circuit, electricity storage into a capacitor becomes less likely to be done, because of the following reasons.
For the purpose of explanation, let us consider a case where the voltage-doubling rectifier circuit of a first power-generation circuital unit and the rectifier circuit of a second power-generation circuital unit are connected in series. In this instance, in the first power-generation circuital unit, a first circuit, in which a first-direction current is flowed in a capacitor by an output of alternating voltages by a power generation apparatus, in the same manner as a case of being used conventionally as a stand-alone power generation circuit. By forming the first circuit, electricity has been stored in a capacitor of the voltage-doubling rectifier circuit.
However, by connecting a plurality of power-generation circuital units in series, a second circuit, in which a current flows in the capacitor in a direction opposite to the first direction, is formed, in addition to the first circuit. The second circuit is a circuit which intervenes between a load instrument and the rectifier circuit in the other power-generation circuital unit. When power-generation circuital units including a voltage-doubling rectifier circuit are connected in series, it has not been possible to securely store electric charges, which a power generation apparatus has output, in the capacitors, due to the formation of the first circuit and second circuit in which the directions of the flowing current are different from one another. Consequently, regardless of having connected the power-generation circuital units in series, an output voltage comes to decline adversely, and accordingly it has been difficult to enhance it.
Moreover, the present inventors investigated outputting a desired voltage to a load instrument for a long period of time, in a case where each of power generation apparatuses generates electricity in timing different from each other as set forth in Japanese Patent Gazette No. 4905820. In a case where a plurality of power generation apparatuses are switched to be connected in series, or to be connected in parallel, to store electricity in a common electricity storage portion as set forth in Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2013-102639, electric powers generated by the multiple power generation apparatuses come to be consumed equally, because all of the power generation apparatus are connected to the common electricity storage portion. Therefore, with the construction, it is not possible to output a desired voltage for a sufficiently-long period of time.
An object of the present invention is to provide, while using a voltage-doubling rectifier circuit, a power generation system enabling electricity to be stored in the voltage-doubling rectifier circuit securely, when connecting a plurality of power-generation circuital units in series.